Precise repeatable setting of color characteristics for lighting applications

ABSTRACT

A desired color of illumination of a subject is achieved by determining settings for color inputs and applying those setting to one or more systems that generate and mix colors of light, so as to provide combined light of the desired character. In the examples of appropriate systems, an optical integrating cavity diffusely reflects light of three or more colors, and combined light emerging from an aperture of the cavity illuminates the subject. System settings for amounts of the different colors of the input lights are easily recorded for reuse or for transfer and use in other systems.

RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.10/555,094, filed Nov. 2, 2005, now U.S. Pat. No. 7,497,590 which is aU.S. National Phase under 35 U.S.C. §371 of International applicationNo. PCT/US2005/014107, filed Apr. 26, 2005 which claims priority fromU.S. patent application Ser. No. 10/832,464 filed on Apr. 27, 2004, nowU.S. Pat. No. 6,995,355; and U.S. patent application Ser. No. 10/555,094is also Continuation-In-Part claiming priority from U.S. patentapplication Ser. No. 10/832,464 filed on Apr. 27, 2004, now U.S. Pat.No. 6,995,355, the disclosure of which is incorporated by referenceherein.

TECHNICAL FIELD

The present subject matter relates to relatively precise, repeatabletechniques to provide radiant energy having a selectable spectralcharacteristic (e.g. a selectable color characteristic), by selectingand combining amounts of light energy of different wavelengths fromdifferent sources.

BACKGROUND

An increasing variety of lighting applications require a preciselycontrolled spectral characteristic of the radiant energy. Applicationsfor product illumination and photography have traditionally used colorfilters, to control the color of illumination, so as to provide certaindesired lighting effects. Other approaches have used different whitelight sources, e.g. to provide somewhat warmer or cooler illumination,for different applications. However, color filters or selection ofdifferent sources providing somewhat different color temperatureprovides only very coarse control of the spectral characteristics of theapplied light. Also, use of selected light sources compromisesrepeatability, as the spectral characteristic of the light often varieswith the age of the particular light sources. Many illuminationapplications would benefit from a technique to more precisely controlthe spectral characteristics of illumination.

It has long been known that combining the light of one color with thelight of another color creates a third color. For example, differentamounts of the commonly used primary colors Red, Green and Blue can becombined to produce almost any color in the visible spectrum. Adjustmentof the amount of each primary color enables adjustment of the spectralproperties of the combined light stream. Recent developments forselectable color systems have utilized light emitting diodes as thesources of the different light colors.

Light emitting diodes (LEDs) were originally developed to providevisible indicators and information displays. For such luminanceapplications, the LEDs emitted relatively low power. However, in recentyears, improved LEDs have become available that produce relatively highintensities of output light. These higher power LEDs, for example, havebeen used in arrays for traffic lights and are beginning to be deployedin more traditional illumination and task lighting applications. Today,LEDs are available in almost any color in the color spectrum.

Systems are known which combine controlled amounts of projected lightfrom at least two LEDs of different primary colors to provide light of aselected color characteristic. Attention is directed, for example, toU.S. Pat. Nos. 6,459,919, 6,166,496 and 6,150,774. Typically, suchsystems have relied on using pulse-width modulation or other modulationof the LED driver signals to adjust the intensity of each LED coloroutput. U.S. Pat. No. 6,340,868 to Lys et al. suggests that an LEDlighting assembly with pulse width modulated current control may beprogrammed to compensate for changes in color temperature, through afeedback mechanism. The modulation requires complex circuitry toimplement. Also, such prior systems have relied on direct radiation orillumination from the individual source LEDs. In some applications, theLEDs may represent undesirably bright sources if viewed directly. Also,the direct illumination from LEDs providing multiple colors of light hasnot provided optimum combination throughout the field of illumination.In some systems, the observer can see the separate red, green and bluelights from the LEDs at short distances from the fixture, even if theLEDs are covered by a translucent diffuser. Integration of colors by theeye becomes effective only at longer distances.

Another problem arises from long-term use of LED type light sources. Asthe LEDs age, the output intensity for a given input level of the LEDdrive current decreases. As a result, it may be necessary to increasepower to an LED to maintain a desired output level. This increases powerconsumption. In some cases, the circuitry may not be able to provideenough light to maintain the desired light output level. As performanceof the LEDs of different colors declines differently with age (e.g. dueto differences in usage), it may be difficult to maintain desiredrelative output levels and therefore difficult to maintain the desiredspectral characteristics of the combined output. The output levels ofLEDs also vary with actual temperature (thermal) that may be caused bydifference in ambient conditions or different operational heating and/orcooling of different LEDs. Temperature induced changes in performancecause changes in the spectrum of light output.

Another problem with existing multi-color LED systems arises fromcontrol of the overall system output intensity. In existing systems, toadjust the combined output intensity, e.g. to reduce or increase overallbrightness, the user must adjust the LED power levels. However, LEDspectral characteristics change with changes in power level. If thelight colors produced by the LEDs change, due to a power leveladjustment, it becomes necessary to adjust the modulations to compensatein order to achieve the same spectral characteristic.

U.S. Pat. No. 6,007,225 to Ramer et al. (Assigned to Advanced OpticalTechnologies, L.L.C.) discloses a directed lighting system utilizing aconical light deflector. At least a portion of the interior surface ofthe conical deflector has a specular reflectivity. In several disclosedembodiments, the source is coupled to an optical integrating cavity; andan outlet aperture is coupled to the narrow end of the conical lightdeflector. This patented lighting system provides relatively uniformlight intensity and efficient distribution of light over a field ofillumination defined by the angle and distal edge of the deflector.However, this patent does not discuss particular color combinations oreffects.

Hence, a need still exists for a technique to efficiently combine energyfrom multiple sources having multiple wavelengths and direct the radiantenergy effectively toward a desired field of illumination, in a mannerthat allows relatively precise, repeatable control of the spectralcharacter of the resulting illumination. A related need still exists forsuch a system that does not require complex electronics (e.g. modulationcircuitry) to control the intensity of the energy output from thesources of the radiant energy of different wavelengths. A need alsoexists for a technique to effectively set and maintain a desiredspectral character of the combined output, e.g. as the performance ofthe source(s) changes with age or power or temperature, preferablywithout requiring excessive power levels.

SUMMARY

Techniques are disclosed herein, for determining settings for colorinputs, to provide a desired illumination of a subject and for applyingthose settings to one or more systems that generate and mix the colorinputs so as to provide combined light of the desired character.

Hence, a first disclosed method of illuminating a subject with light ofa desired color characteristic involves determining settings relating toamounts of three colors of light, for providing the desired colorcharacteristic. Data is recorded, which corresponds to the determinedsettings; and the data is transferred to a lighting system for use inilluminating the subject. In response to the data, the lighting systemgenerates light of the three colors, in amounts corresponding to thedetermined settings. The method also involves diffusely reflecting thegenerated light of the three colors within a cavity, to produce combinedlight containing the three colors of light in amounts proportional tothe determined settings. Combined light emerges through an aperture ofthe cavity, to illuminate the subject with light of the desired colorcharacteristic for human observation of the illuminated object.

Human observation of the illuminated subject may involve direct viewing.In several examples, an observer views instances of an illuminatedproduct on display in a store or the like. However, observation also maybe indirect. For example, a person may be photographed whileilluminated, and the picture distributed or communicated by any knownmeans.

An example of the lighting system includes an optical cavity, having adiffusely reflective interior surface and an aperture for allowingemission of combined radiant energy. Sources supply light of thedifferent colors into the interior of the cavity. The cavity effectivelycombines the energy of the different colors, so that the combined lightemitted through the aperture includes the radiant energy of the variouscolors.

The sources can include any color or wavelength, but typically theexamples use red, green, and blue light sources. One or more sources mayalso provide substantially white light. The integrating or mixingcapability of the optical cavity serves to project light that appears tobe white or substantially white to the human observer but exhibits adesired variation in color characteristic, by adjusting the intensity ofthe various sources coupled to the cavity. Hence, it is possible tocontrol color temperature and a difference (Δ) from the standard colorcombination for that temperature.

A lighting system using an apparatus as disclosed herein will include acontrol circuit, coupled to the sources for establishing outputintensity of radiant energy of each of the sources. Control of theintensity of emission of the sources sets a spectral characteristic ofthe combined radiant energy emitted through the aperture. If the fixtureincludes a variable iris, the output intensity may be adjusted byadjustment of the iris opening without the need to change the powerlevels of the sources, and thus without impact on the spectralcharacteristic of the output.

In the examples, each source typically comprises one or more lightemitting diodes (LEDs). It is possible to install any desirable numberof LEDs. Hence, In several examples, the sources may comprise one ormore LEDs for emitting light of a first color, and one or more LEDs foremitting light of a second color, wherein the second color is differentfrom the first color. In a similar fashion, the apparatus may includeadditional LED sources of a third color, a fourth color, etc. To achievethe highest color-rendering index (CRI), the LED array may include LEDsof colors that effectively cover the entire visible spectrum. Thelighting system works with the totality of light output from a family ofLEDs. However, to provide color adjustment or variability, it is notnecessary to control the output of individual LEDs, except as theintensity of each contributes to the totality. For example, it is notnecessary to modulate the LED outputs. Also, the distribution pattern ofthe LEDs is not significant. The LEDs can be arranged in any manner tosupply radiant energy within the optical cavity, although typicallydirect view from outside the fixture is avoided.

An exemplary system includes a number of “sleeper” LEDs that would beactivated only when needed, for example, to maintain the light output,color, color temperature or thermal temperature. Hence, examples arealso disclosed in which the first color LEDs comprise one or moreinitially active LEDs for emitting light of the first color and one ormore initially inactive LEDs for emitting light of the first color on anas needed basis. Similarly, the second color LEDs include one or moreinitially active LEDs for emitting light of the second color and one ormore initially inactive LEDs for emitting light of the second color onan as needed basis. In a similar fashion, the apparatus may includeadditional active and inactive LED sources of a third color, fourthcolor, etc. or active and inactive LED sources of white light.

As noted in the background, as LEDs age, they continue to operate, butat a reduced output level. The color characteristic may also vary withpower level and/or temperature. The use of the sleeper LEDs greatlyextends the lifecycle and the operational range of the fixtures.Activating a sleeper (previously inactive) LED, for example, providescompensation for the decrease in output of the originally active LED.There is also more flexibility in the range of intensities that thefixtures may provide under various operating conditions.

A number of different examples of control circuits are discussed below.In one example, the control circuitry comprises a color sensor coupledto detect color distribution in the combined radiant energy. Associatedlogic circuitry, responsive to the detected color distribution, controlsthe output intensity of the various LEDs, so as to provide a desiredcolor distribution in the integrated radiant energy. In an example usingsleeper LEDs, the logic circuitry is responsive to the detected colordistribution to selectively activate one or more of the inactive lightemitting diodes as needed, to maintain the desired color distribution inthe combined light that illuminates the subject.

A number of other control circuit features also are disclosed. Forexample, the control circuitry may include an appropriate device formanually setting the desired spectral characteristic, for example, oneor more variable resistors or one or more dip switches, to allow a userto define or select the desired color distribution. Automatic controlsalso are envisioned. For example, the control circuitry may include adata interface coupled to the logic circuitry, for receiving datadefining the desired color distribution. Such an interface would allowinput of control data from a separate or even remote device, such as apersonal computer, personal digital assistant or the like. A number ofthe devices, with such data interfaces, may be controlled from a commoncentral location or device. Examples are also disclosed with automaticselection data input, e.g. by sensing data recorded on or in associationwith a subject the system will illuminate.

A related method disclosed herein involves generating a variable amountof light of a first wavelength and a variable amount of light of asecond wavelength. The two wavelengths are different. The light of thesetwo wavelengths is optically combined and used to illuminate thesubject. This method involves adjusting the amount of the light of eachwavelength, to achieve a color characteristic of a desired illuminationof the subject. The amount of light of each wavelength in the combinedlight used to achieve the desired illumination of the subject isrecorded. It then becomes possible to set a lighting system to generatethe recorded amount of light of each wavelength, and the resulting lightis optically combined to produce a combined light output correspondingto the desired illumination. Hence, irradiation of the subject with thecombined light output from the lighting system achieves the desiredillumination of the subject using the lighting system.

Another method disclosed herein serves to illuminate a subject withlight of a desired color characteristic. This method involves settingfirst and second amounts for light of two different wavelengths andoperating sources to generate light of both wavelengths at intensitiescorresponding to the respective set amounts. The first and second setamounts correspond to the desired color characteristic for theillumination of the subject. The method also entails diffuselyreflecting the generated light of the two wavelengths within a cavity,to produce combined light containing amounts of light of the first andsecond wavelengths in proportion to the first and second set amounts.Emission of at least a portion of the combined light through an apertureof the cavity illuminates the subject, with light of the desired colorcharacteristic.

Additional objects, advantages and novel features of the examples willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing and the accompanying drawings or may be learned by productionor operation of the examples. The objects and advantages of the presentsubject matter may be realized and attained by means of themethodologies, instrumentalities and combinations particularly pointedout in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present concepts, by way of example only, not by way of limitations.In the figures, like reference numerals refer to the same or similarelements.

FIG. 1 illustrates an example of a radiant energy emitting system, withcertain elements thereof shown in cross-section.

FIG. 2(A) is a flow diagram useful in understanding a process of settinga desired color characteristic for application in one or more of thesystems of FIG. 1.

FIG. 2(B) depicts the chromaticity standard and black body curve.

FIG. 2(C) is an enlarged view of a representation of the black bodycurve.

FIG. 3 illustrates another example of a radiant energy emitting system,with certain elements thereof shown in cross-section.

FIG. 4 is a bottom view of the fixture in the system of FIG. 3.

FIG. 5 illustrates another example of a radiant energy emitting system,using fiber optic links from the LEDs to the optical integrating cavity.

FIG. 6 illustrates another example of a radiant energy emitting system,utilizing principles of constructive occlusion.

FIG. 7 is a bottom view of the fixture in the system of FIG. 6.

FIG. 8 illustrates another example of a radiant energy emitting system,utilizing principles of constructive occlusion.

FIG. 9 is a top plan view of the fixture in the system of FIG. 8.

FIG. 10 is a functional block diagram of the electrical components, ofone of the radiant energy emitting systems, using programmable digitalcontrol logic.

FIG. 11 is a circuit diagram showing the electrical components, of oneof the radiant energy emitting systems, using analog control circuitry.

FIG. 12 is a diagram, illustrating a number of radiant energy emittingsystems with common control from a master control unit.

FIG. 13 is a cross-sectional view of another example of an opticalcavity LED light fixture, using a collimator, iris and adjustablefocusing system to process the combined light output.

FIG. 14 is a cross-sectional view of another example of an opticalcavity LED light fixture, as might be used for a “wall-washer”application.

FIG. 15 is an isometric view of an extruded section of a fixture havingthe cross-section of FIG. 14.

FIG. 16 is a cross-sectional view of another example of an opticalcavity LED light fixture, as might be used for a “wall-washer”application, using a combination of a white light source and a pluralityof primary color light sources.

FIG. 17 is a cross-sectional view of another example of an opticalcavity LED light fixture, in this case using a deflector and acombination of a white light source and a plurality of primary colorlight sources.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent to those skilledin the art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

Reference now is made in detail to the examples illustrated in theaccompanying drawings and discussed below. FIG. 1 is a cross-sectionalillustration of a radiant energy distribution apparatus or system 10.For illumination or task lighting applications, the apparatus emitslight in the visible spectrum, although the system 10 may be used forother applications and/or with emissions in or extending into theinfrared and/or ultraviolet portions of the radiant energy spectrum.

The illustrated system 10 includes an optical cavity 11 having adiffusely reflective interior surface, to receive and combine radiantenergy of different colors/wavelengths. The cavity 11 may have variousshapes. The illustrated cross-section would be substantially the same ifthe cavity is hemispherical or if the cavity is semi-cylindrical withthe cross-section taken perpendicular to the longitudinal axis. Theoptical cavity in the examples discussed below is typically an opticalintegrating cavity.

The disclosed apparatus may use a variety of different structures orarrangements for the optical integrating cavity, examples of which arediscussed below relative to FIGS. 3-9 and 13-17. At least a substantialportion of the interior surface(s) of the cavity exhibit(s) diffusereflectivity. It is desirable that the cavity surface have a highlyefficient reflective characteristic, e.g. a reflectivity equal to orgreater than 90%, with respect to the relevant wavelengths. In theexample of FIG. 1, the surface is highly diffusely reflective to energyin the visible, near-infrared, and ultraviolet wavelengths.

The cavity 11 may be formed of a diffusely reflective plastic material,such as a polypropylene having a 97% reflectivity and a diffusereflective characteristic. Such a highly reflective polypropylene isavailable from Ferro Corporation—Specialty Plastics Group, Filled andReinforced Plastics Division, in Evansville, Ind. Another example of amaterial with a suitable reflectivity is SPECTRALON. Alternatively, theoptical integrating cavity may comprise a rigid substrate having aninterior surface, and a diffusely reflective coating layer formed on theinterior surface of the substrate so as to provide the diffuselyreflective interior surface of the optical integrating cavity. Thecoating layer, for example, might take the form of a flat-white paint orwhite powder coat. A suitable paint might include a zinc-oxide basedpigment, consisting essentially of an uncalcined zinc oxide andpreferably containing a small amount of a dispersing agent. The pigmentis mixed with an alkali metal silicate vehicle-binder, which preferablyis a potassium silicate, to form the coating material. For moreinformation regarding the exemplary paint, attention is directed to U.S.patent application Ser. No. 09/866,516, which was filed May 29, 2001, byMatthew Brown, which issued as U.S. Pat. No. 6,700,112 on Mar. 2, 2004.

For purposes of the discussion, the cavity 11 in the apparatus 10 isassumed to be hemispherical. In the example, a hemispherical dome 13 anda substantially flat cover plate 15 form the optical cavity 11. At leastthe interior facing surfaces of the dome 13 and the cover plate 15 arehighly diffusely reflective, so that the resulting cavity 11 is highlydiffusely reflective with respect to the radiant energy spectrumproduced by the device 10. As a result, the cavity 11 is an integratingtype optical cavity. Although shown as separate elements, the dome andplate may be formed as an integral unit.

The optical integrating cavity 11 has an aperture 17 for allowingemission of combined radiant energy. In the example, the aperture 17 isa passage through the approximate center of the cover plate 15, althoughthe aperture may be at any other convenient location on the plate 15 orthe dome 13. Because of the diffuse reflectivity within the cavity 11,light within the cavity is integrated before passage out of the aperture17. In the example, the apparatus 10 is shown emitting the combinedradiant energy downward through the aperture 17, for convenience.However, the apparatus 10 may be oriented in any desired direction toperform a desired application function, for example to provide visibleillumination of persons or objects in a particular direction or locationwith respect to the fixture. Also, the optical integrating cavity 11 mayhave more than one aperture 17, for example, oriented to allow emissionof integrated light in two or more different directions or regions.

The apparatus 10 also includes sources of radiant energy of differentwavelengths. In the first example, the sources are LEDs 19, two of whichare visible in the illustrated cross-section. The LEDs 19 supply radiantenergy into the interior of the optical integrating cavity 11. As shown,the points of emission into the interior of the optical integratingcavity are not directly visible through the aperture 17. At least thetwo illustrated LEDs emit radiant energy of different colors, e.g. Red(R) and Green (G). Additional LEDs of the same or different colors maybe provided. A typical example includes a Blue (B) LED. To achieve thehighest color rendering index (CRI), the LED array may include LEDs ofvarious wavelengths that cover virtually the entire visible spectrum.Examples with additional sources of substantially white light arediscussed later. The cavity 11 effectively integrates the energy ofdifferent colors, so that the integrated or combined radiant energyemitted through the aperture 17 includes the radiant energy of all thevarious wavelengths in relative amounts substantially corresponding tothe relative intensities of input into the cavity 11.

The integrating or mixing capability of the cavity 11 serves to projectlight of any color, including white light, by adjusting the intensity ofthe various sources coupled to the cavity. For example, in white lightillumination applications, it is possible to control color temperatureand to control differences in color from standard or normal values atthe various temperatures. The system 10 works with the totality of lightoutput from a family of LEDs 19. However, to provide color adjustment orvariability, it is not necessary to control the output of individualLEDs, except as they contribute to the totality. For example, it is notnecessary to modulate the LED outputs. Also, the distribution pattern ofthe individual LEDs and their emission points into the cavity are notsignificant. The LEDs 19 can be arranged in any manner to supply radiantenergy within the cavity, although it is preferred that direct view ofthe LEDs from outside the fixture is minimized or avoided.

In this example, light outputs of the LED sources 19 are coupleddirectly to openings at points on the interior of the cavity 11, to emitradiant energy directly into the interior of the optical integratingcavity. The LEDs may be located to emit light at points on the interiorwall of the element 13, although preferably such points would still bein regions out of the direct line of sight through the aperture 17. Forease of construction, however, the openings for the LEDs 19 are formedthrough the cover plate 15. On the plate 15, the openings/LEDs may be atany convenient locations.

The apparatus 10 also includes a control circuit 21 coupled to the LEDs19 for establishing output intensity of radiant energy of each of theLED sources. The control circuit 21 typically includes a power supplycircuit coupled to a source, shown as an AC power source 23. The controlcircuit 21 also includes an appropriate number of LED driver circuitsfor controlling the power applied to each of the individual LEDs 19 andthus the intensity of radiant energy supplied to the cavity 11 for eachdifferent wavelength. Control of the intensity of emission of thesources sets a spectral characteristic of the combined radiant energyemitted through the aperture 17 of the optical integrating cavity. Thecontrol circuit 21 may be responsive to any one or more of a number ofdifferent user or automatic data input signals for setting the colorintensities, as represented generically by the arrow in FIG. 1. Althoughnot shown in this simple example, feedback may also be provided, forexample, based on sensing of color or sensing of thermal temperature.Also, the system will often include initially active sources as well asspare initially inactive sources (“sleepers”), to provide a wideroperational range and enable adjustment to compensate for LEDdegradation with age, power or thermal temperature. Specific examples ofthe control circuitry and use of such sleepers are discussed in moredetail later.

The aperture 17 may serve as the system output, directing integratedcolor light to a desired area or region to be illuminated. Although notshown in this example, the aperture 17 may have a grate, lens ordiffuser (e.g. a holographic element) to help distribute the outputlight and/or to close the aperture against entry of moisture of debris.For some applications, the system 10 includes an additional deflector todistribute and/or limit the light output to a desired field ofillumination. A later embodiment, for example, uses a colliminator. Thecolor integrating energy distribution apparatus may also utilize one ormore conical deflectors having a reflective inner surface, toefficiently direct most of the light emerging from a light source into arelatively narrow field of view.

Hence, the exemplary apparatus shown in FIG. 1 also comprises conicaldeflector 25. A small opening at a proximal end of the deflector iscoupled to the aperture 17 of the optical integrating cavity 11. Thedeflector 25 has a larger opening 27 at a distal end thereof. The angleand distal opening of the conical deflector 25 define an angular fieldof radiant energy emission from the apparatus 10. Although not shown,the large opening of the deflector may be covered with a transparentplate or lens, or covered with a grating, to prevent entry of dirt ordebris through the cone into the system and/or to further process theoutput radiant energy.

The conical deflector 25 may have a variety of different shapes,depending on the particular lighting application. In the example, wherecavity 11 is hemispherical, the cross-section of the conical deflectoris typically circular. However, the deflector may be somewhat oval inshape. In applications using a semi-cylindrical cavity, the deflectormay be elongated or even rectangular in cross-section. The shape of theaperture 17 also may vary, but will typically match the shape of thesmall end opening of the deflector 25. Hence, in the example, theaperture 17 would be circular. However, for a device with asemi-cylindrical cavity and a deflector with a rectangularcross-section, the aperture may be rectangular.

The deflector 25 comprises a reflective interior surface 29 between thedistal end and the proximal end. In some examples, at least asubstantial portion of the reflective interior surface 29 of the conicaldeflector exhibits specular reflectivity with respect to the integratedradiant energy. As discussed in U.S. Pat. No. 6,007,225, for someapplications, it may be desirable to construct the deflector 25 so thatat least some portion(s) of the inner surface 29 exhibit diffusereflectivity or exhibit a different degree of specular reflectivity(e.g., quasi-secular), so as to tailor the performance of the deflector25 to the particular application. For other applications, it may also bedesirable for the entire interior surface 29 of the deflector 25 to havea diffuse reflective characteristic. In such cases, the deflector 25 maybe constructed using materials similar to those taught above forconstruction of the optical integrating cavity 11.

In the illustrated example, the large distal opening 27 of the deflector25 is roughly the same size as the cavity 11. In some applications, thissize relationship may be convenient for construction purposes. However,a direct relationship in size of the distal end of the deflector and thecavity is not required. The large end of the deflector 25 may be largeror smaller than the cavity structure. As a practical matter, the size ofthe cavity is optimized to provide the integration or combination oflight colors from the desired number of LED sources 19. The size, angleand shape of the deflector determine the area that will be illuminatedby the combined or integrated light emitted from the cavity 11 via theaperture 17.

A system such as that shown in FIG. 1 enables precise, repeatablecontrol of the color characteristics of the light output by setting theintensity of each source. In many cases, the system may be controlled soas to produce light that the human observer will consider as white, yetwith subtle adjustments of color to provide desire illumination effects.

Settings for a desirable color are easily reused or transferred from onesystem/fixture to another. If color/temperature/balance offered byparticular settings are found desirable, e.g. to light a particularproduct on display or to illuminate a particular person or object in astudio or theater, it is a simple matter to record those settings andapply them at a later time. Similarly, such settings may be readilyapplied to another system or fixture, e.g. if the product is displayedat another location or if the person is appearing in a different studioor theater.

FIG. 2(A) is a simple flow chart useful in understanding thesetechniques for determining and setting desired color characteristics,for use in one or more lighting systems like the system 10. As shown atS1, the method of illuminating involves determining settings relating toamounts of three (or more) colors of light, for providing the desiredcolor characteristic. The settings may be determined in a variety ofways. The settings may be estimated or determined by photometricmeasurements taken from the subject.

The example shows a series of sub-steps S11 to S14 for testingillumination of the subject in question and observing the results, untila desired effect is achieved. Hence, the subject is illuminated atS11-S12. Of note, the step S11 involves generating light of the three ormore colors, which are integrated or mixed at S12 (using a systemsimilar to system 10 of FIG. 1) for illumination of the subject. At S13,a determination is made as to whether the illumination achieves thedesired color characteristic. The determination may be automatic, butoften it is a subjective determination by a human observer throughdirect or indirect observation. If not, the process flows to step S14,at which the color amounts, e.g. the amounts of the RGB light input areadjusted. Illumination of the subject continues at S11 and S12.

The process of illuminating and adjusting the color amounts continuesthrough sub-steps S11-S14, until the observer determines that thelighting provides the desired effects on the subject. In that event, theprocess at step S13 returns to the main routine, at which processingflows from step S1 to step S2. In step S2, data, which corresponds tothe determined settings that produced the desired illumination, isrecorded.

In a typical case, the combined light will generally be white to anobserver, e.g. when looking directly at the subject or viewing a pictureof the illuminated subject. However, the adjustment of the color amountsprovides for subtle variations, that support the desired illumination ofthe individual subject. To appreciate these subtleties and how thesettings may be recorded, it may be helpful to review some aspects ofstandard colorimetry.

FIG. 2(B) shows an approximation of the 1931 version of the CIEChromaticity Diagram. The X axis represents red, and the Y axisrepresents green. The Z axis would be perpendicular to the plane of thediagram, and the Z axis represents blue. However, the three numbers mustadd up to 1, so typically, the diagram shows only the X and Y values.The Z value is computed from X and Y (X+Y+Z=1). The space within theshark-fin shaped boundary curve B1 represents the portion of the radiantenergy spectrum that is typically visible to a human. Any color of lightwithin the visible spectrum can be represented by values of X,Y,Z wherethe X-Y point falls within or on the boundary of the curve B1 on thischromaticity chart. Formulae are also known for converting X, Y, Zchromaticity to/from primary color values, such as proportional amountsof red (R), green (G) and blue (B) or cyan (C), magenta (M) and yellow(Y), that will produce visible light corresponding to any point in or onthe curve B1. Hence, X,Y,Z values or corresponding values for primarycolors such as RGB can be used for any visible light, in this case, asdetermined at S1 and recorded at S2 in the process of FIG. 2(A) toproduce the desired color characteristic for illumination of thesubject. Of course other metrics may be used to provide datarepresentative of the color settings.

Light that a human perceives as white or substantially white often ismeasured by a color temperature corresponding to a point on a standardcurve approximated at B2 in the illustrations. The black body curve B2corresponds to a locus of points on the diagram that represent lightemitted from a black body radiator at various temperatures, measured indegrees Kelvin. Of note for purposes of this discussion, light at pointsalong the section of this curve corresponding approximately to 1800 to6500 degrees Kelvin is typically perceived as visible white light, whenobjects illuminated by the light are viewed or otherwise observed by ahuman. A red tinged sunrise, for example, often is about 1800° K, onthis curve. Normal sunlight, e.g. around midday on a clear day, is about5600° K. FIG. 2(C) provides an enlargement of the curve B2.

For many desirable illumination effects, the light will appear white tothe observer but will not fall precisely on the black body curve. Theenlarged view of the curve shows two examples, at or near the 5600° Ktemperature for daylight illumination. At values around thistemperature, the light will still appear much like daylight does, whenan observer views an illuminated subject. However, changes in theprecise X,Y,Z values (and corresponding RGB values or other componentintensity values) produces subtle differences in color and thusdifferences in the illumination effect on the subject. The magnitudes ofthe differences are exaggerated somewhat in the drawing, for ease ofillustration.

In the examples of FIG. 2(C), a white light value may be specified interms of temperature (° K), which falls along the curve; and adifference is expressed as an X,Y,Z vector (ΔUV). Two such vectors areshown by way of example, one negative and one positive. The −ΔUVprovides somewhat warmer illumination, as for example, might be used tohighlight red elements of a product or product display arrangement. The+ΔUV provides somewhat cooler illumination, as for example, as might beused to highlight blue or green elements of a product or product displayarrangement.

Returning to the process flow of FIG. 2(A), the determining step S1identifies a particular visible color of light, corresponding to a pointin the visible spectrum on the chart of FIG. 2(B), which provides thedesired color characteristic for illumination of the particular subject.In step S2, data defining the point in the visible spectrum is recorded.In our example, the data may be X,Y,Z coordinates or correspondingvalues for relative RGB intensities. For white light illuminationexamples, the setting typically corresponds to a color temperature onthe black body curve B2 and a difference vector ΔUV. The temperature andΔUV vector may be used as the recorded data.

At S3, the recorded data is transferred to a lighting system for use inilluminating the subject. The data may be sent to a single system, butin many applications, the data is sent to a number of such systems. Thereceiving stations may be at the same location, at one other location orat many other locations. In response to the data, each lighting systemgenerates light of the various component colors, RGB in our example(S4), in amounts corresponding to the determined settings. Themethodology also involves diffusely reflecting the generated light ofthe colors within a cavity, to produce combined light containing thecolors of light in amounts proportional to the determined settings (asrepresented by the step S5 in the drawing). Combined light emergesthrough an aperture of the cavity, to illuminate the subject with lightof the desired color characteristic.

Although the receiving systems may be the same, they need not beidentical or even particularly similar to each other, so long as theyare capable of generating the specified colors in the proportionsindicated by the setting data and combine those colors of light in anintegrating chamber for output towards an example of the intendedsubject. If different color sources are used, e.g. CMY instead of RGB,it would only be necessary to translate the settings for the RGB typesystem to corresponding settings for the CMY system. As the amounts ofeach color of light are controlled and integrated, each lighting systemwill illuminate the subject in substantially the same manner. In thisway, the desired illumination effect is repeated by each system and/oreach time a system illuminates an instance of the subject using the datafor the color settings.

The methods for defining and transferring set conditions, e.g. forproduct lighting or personal lighting, can utilize manual recordings ofsettings and input of the settings to the different lighting systems.However, it is preferred to utilize digital control, in systems such asdescribed below relative to FIGS. 10 and 12. Once input to a givenlighting system, a particular set of parameters for a product orindividual become a ‘preset’ lighting recipe stored in digital memory,which can be quickly and easily recalled and used each time that theparticular product or person is to be illuminated. When using thedigital implementation, the transfer of settings can be doneautomatically, for example, by inclusion of the setting data on amachine readably media incorporated into or included with a product anddetectable by equipment associated with the computerized lightingcontrol systems. Examples of such media include radio-frequency (RF)identification tags and bar codes. Other implementations may distributethe setting data via network communication.

It may be helpful to consider some examples of applications of theseillumination techniques.

For a product, assume that a company will offer a new soft drink in acan having a substantial amount of red product markings. The company cantest the product under lighting using one or more fixtures as describedherein, to determine the optimum color to achieve a desired brilliantdisplay. In a typical case, the light will generally be white to theobserver. In the case of the red product container, the white light willhave a relatively high level of red, to make the red markings seem toglow when the product is viewed by the casual observer/customer. Whenthe company determines the appropriate settings for the new product, itcan distribute those settings to the stores that will display and sellthe product. The stores will use other fixtures of any type disclosedherein. The fixtures in the stores need not be of the exact same typethat the company used during product testing. Each store uses thesettings received from the company to establish the spectralcharacteristic(s) of the lighting applied to the product by the store'sfixture(s), in our example, so that each product display provides thedesired brilliant red illumination of the company's new soft drinkproduct.

Consider now a studio lighting example for an actor or newscaster. Theperson is tested under lighting using one or more fixtures as describedherein, to determine the optimum color to achieve desired appearance invideo or film photography of the individual. Again, the light willgenerally appear white to the human observer seeing the person in thestudio an/or seeing the resulting video or photograph. However, eachperson will appear better at somewhat different temperature (° K) andoffset (ΔUV). One person might appear more healthy and natural underwarmer light, whereas another might appear better under bluer/colderwhite light. After testing to determine the person's best light colorsettings, the settings are recorded. Each time the person appears underany lighting using the systems disclosed herein, in the same or adifferent studio, the technicians operating the lights can use the samesettings to control the lighting and light the person with light ofexactly the same spectral characteristic(s). Similar processes may beused to define a plurality of desirable lighting conditions for theactor or newscaster, for example, for illumination for different moodsor different purposes of the individual's performances or for liveappearances or for different photographic equipment (e.g. video asopposed to film).

FIGS. 3 and 4 illustrate another example of a radiant energydistribution apparatus or system. FIG. 3 shows the overall system 30,including the fixture and the control circuitry. The fixture is shown incross-section. FIG. 4 is a bottom view of the fixture. The system 30 isgenerally similar the system 10. For example, the system 30 may utilizeessentially the same type of control circuit 21 and power source 23, asin the earlier example. However, the shape of the optical integratingcavity and the deflector are somewhat different.

The optical integrating cavity 31 has a diffusely reflective interiorsurface. In this example, the cavity 31 has a shape corresponding to asubstantial portion of a cylinder. In the cross-sectional view of FIG. 3(taken across the longitudinal axis of the cavity), the cavity 31appears to have an almost circular shape. In this example, the cavity 31is formed by a cylindrical element 33. At least the interior surface ofthe element 33 is highly diffusely reflective, so that the resultingoptical cavity 31 is highly diffusely reflective and functions as anintegrating cavity, with respect to the radiant energy spectrum producedby the system 30.

The optical integrating cavity 31 has an aperture 35 for allowingemission of combined radiant energy. In this example, the aperture 35 isa rectangular passage through the wall of the cylindrical element 33.Because of the diffuse reflectivity within the cavity 31, light withinthe cavity is integrated before passage out of the aperture 35.

The apparatus 30 also includes sources of radiant energy of differentwavelengths. In this example, the sources comprise LEDs 37, 39. The LEDsare mounted in openings through the wall of the cylindrical element 33,to essentially form two rows of LEDs on opposite sides of the aperture35. The positions of these openings, and thus the positions of the LEDs37 and 39, typically are such that the LED outputs are not directlyvisible through the aperture 35, otherwise the locations are a matter ofarbitrary choice.

Thus, the LEDs 37 and 39 supply radiant energy into the interior of theoptical integrating cavity 31, through openings at points on theinterior surface of the optical integrating cavity not directly visiblethrough the aperture 35. A number of the LEDs emit radiant energy ofdifferent wavelengths. For example, arbitrary pairs of the LEDs 37, 39might emit four different colors of light, e.g. Red, Green and Blue asprimary colors and a fourth color chosen to provide an increasedvariability of the spectral characteristic of the integrated radiantenergy. One or more white light sources, e.g. white LEDs, also may beprovided.

Alternatively, a number of the LEDs may be initially active LEDs,whereas others are initially inactive sleeper LEDs. For example, theinitially active LEDs might include two Red LEDs, two Green LEDs and aBlue LED; and the sleeper LEDs might include one Red LED, one Green LEDand one Blue LED.

The control circuit 21 controls the power provided to each of the LEDs37 and 39. The cavity 31 effectively integrates the energy of differentwavelengths, from the various LEDs 37 and 39, so that the integratedradiant energy emitted through the aperture 35 includes the radiantenergy of all the various wavelengths. Control of the intensity ofemission of the sources, by the control circuit 21, sets a spectralcharacteristic of the combined radiant energy emitted through theaperture 35. If sleeper LEDs are provided, the control also activatesone or more dormant LEDs, on an “as-needed” basis, when extra output ofa particular wavelength or color is required. As discussed later withregard to an exemplary control circuit, the system 30 could have a colorsensor coupled to detect color of the combined light and providefeedback to the control circuit 21.

The color integrating energy distribution apparatus 30 may also includea deflector 41 having a specular reflective inner surface 43, toefficiently direct most of the light emerging from the aperture into arelatively narrow field of view. The deflector 41 expands outward from asmall end thereof coupled to the aperture 35. The deflector 41 has alarger opening 45 at a distal end thereof. The angle of the side wallsof the deflector and the shape of the distal opening 45 of the deflector41 define an angular field of radiant energy emission from the apparatus30.

As noted above, the deflector may have a variety of different shapes,depending on the particular lighting application. In the example, wherethe cavity 31 is substantially cylindrical, and the aperture isrectangular, the cross-section of the deflector 41 (viewed across thelongitudinal axis as in FIG. 3) typically appears conical, since thedeflector expands outward as it extends away from the aperture 35.However, when viewed on-end (bottom view—FIG. 4), the openings aresubstantially rectangular, although they may have somewhat roundedcorners. Alternatively, the deflector 41 may be somewhat oval in shape.The shapes of the cavity and the aperture may vary, for example, to haverounded ends, and the deflector may be contoured to match the aperture.

The deflector 41 comprises a reflective interior surface 43 between thedistal end and the proximal end. In several examples, at least asubstantial portion of the reflective interior surface 43 of the conicaldeflector exhibits specular reflectivity with respect to the combinedradiant energy, although different reflectivity may be provided, asnoted in the discussion of FIG. 1.

In the examples discussed above relative to FIGS. 1, 3 and 4, the LEDsources were coupled directly to openings at the points on the interiorof the cavity, to emit radiant energy directly into the interior of theoptical integrating cavity. It is also envisioned that the sources maybe somewhat separated from the cavity, in which case, the device mightinclude optical fibers or other forms of light guides coupled betweenthe sources and the optical integrating cavity, to supply radiant energyfrom the sources to the emission points into the interior of the cavity.FIG. 5 depicts such a system 50, which uses optical fibers.

The system 50 includes an optical integrating cavity 51, an aperture 53and a deflector with a reflective interior surface 55, similar to thosein the earlier embodiments. The interior surface of the opticalintegrating cavity 51 is highly diffusely reflective, whereas thedeflector surface 55 exhibits a specular reflectivity.

The system 50 includes a control circuit 21 and power source 23, as inthe earlier embodiments. In the system 50, the radiant energy sourcescomprise LEDs 59 of three different wavelengths, e.g. to provide Red,Green and Blue light respectively. The sources may also include one ormore additional LEDs 61, either white or of a different color or for useas ‘sleepers,’ similar to the example of FIGS. 3 and 4. In this example(FIG. 5), the cover plate 63 of the cavity 51 has openings into whichare fitted the light emitting distal ends of optical fibers 65. Theproximal light receiving ends of the fibers 65 are coupled to receivelight emitted by the LEDs 59 (and 61 if provided). In this way, the LEDsources 59, 61 may be separate from the chamber 51, for example, toallow easier and more effective dissipation of heat from the LEDs. Thefibers 65 transport the light from the LED sources 59, 61 to the cavity51. The cavity 51 integrates the different colors of light from the LEDsas in the earlier examples and supplies combined light out through theaperture 53. The deflector, in turn, directs the combined light to adesired field.

Again, the intensity control by the circuit 21 adjusts the amount orintensity of the light of each type provided by the LED sources and thuscontrols the spectral characteristic of the combined light output. Anumber of different examples of control circuits are discussed below. Inone example, the control circuitry comprises a color sensor coupled todetect color distribution in the integrated radiant energy. Associatedlogic circuitry, responsive to the detected color distribution, controlsthe output intensity of the various LEDs, so as to provide a desiredcolor distribution in the integrated radiant energy. In an example usingsleeper LEDs, the logic circuitry is responsive to the detected colordistribution to selectively activate the inactive light emitting diodesas needed, to maintain the desired color distribution in the integratedradiant energy.

To provide a uniform output distribution from the apparatus, it is alsopossible to construct the optical cavity so as to provide constructiveocclusion. Constructive Occlusion type transducer systems utilize anelectrical/optical transducer optically coupled to an active area of thesystem, typically the aperture of a cavity or an effective apertureformed by a reflection of the cavity. The systems utilize diffuselyreflective surfaces, such that the active area exhibits a substantiallyLambertian characteristic. A mask occludes a portion of the active areaof the system, in the examples, the aperture of the cavity or theeffective aperture formed by the cavity reflection, in such a manner asto achieve a desired response or output performance characteristic forthe system. In examples of the present systems using constructiveocclusion, the optical integrating cavity comprises a base, a mask and acavity in either the base or the mask. The mask would have a diffuselyreflective surface facing toward the aperture. The mask is sized andpositioned relative to the active area so as to constructively occludethe active area. It may be helpful to consider two examples usingconstructive occlusion.

FIGS. 6 and 7 depict a first, simple embodiment of a light distributorapparatus or system 70, for projecting integrated multi-wavelength lightwith a tailored intensity distribution, using the principles ofconstructive occlusion. In the cross-section illustration, the system 70is oriented to provide downward illumination. Such a system might bemounted in or suspended from a ceiling or canopy or the like. Thoseskilled in the art will recognize that the designer may choose to orientthe system 70 in different directions, to adapt the system to otherlighting applications.

The lighting system 70 includes a base 73, having or forming a cavity75, and adjacent shoulders 77 and 79, constructed in a manner similar tothe elements forming integrating cavities in the earlier examples. Inparticular, the interior of the cavity 75 is diffusely reflective, andthe down-facing surfaces of shoulders 77 and 79 may be reflective. Ifthe shoulder surfaces are reflective, they may be specular or diffuselyreflective. A mask 81 is disposed between the cavity aperture 85 and thefield to be illuminated. In this symmetrical embodiment, the interiorwall of a half-cylindrical base 73 forms the cavity; therefore theaperture 85 is rectangular. The shoulders 77 formed along the sides ofthe aperture 85 are rectangular. If the base were circular, with ahemispherical cavity, the shoulders typically would form a ring that maypartially or completely surround the aperture.

In many constructive occlusion embodiments, the cavity 75 comprises asubstantial segment of a sphere. For example, the cavity may besubstantially hemispherical, as in earlier examples. However, thecavity's shape is not of critical importance. A variety of other shapesmay be used. In the illustrated example, the half-cylindrical cavity 75has a rectangular aperture, and if extended longitudinally, therectangular aperture may approach a nearly linear aperture (slit).Practically any cavity shape is effective, so long as it has a diffusereflective inner surface. A hemisphere or the illustrated half-cylindershape are preferred for the ease in modeling for the light output towardthe field of intended illumination and the attendant ease ofmanufacture. Also, sharp corners tend to trap some reflected energy andreduce output efficiency.

For purposes of constructive occlusion, the base 73 may be considered tohave an active optical area, preferably exhibiting a substantiallyLambertian energy distribution. Where the cavity is formed in the base,for example, the planar aperture 85 formed by the rim or perimeter ofthe cavity 75 forms the active surface with substantially Lambertiandistribution of energy emerging through the aperture. As shown in alater embodiment, the cavity may be formed in the facing surface of themask. In such a system, the surface of the base may be a diffuselyreflective surface, therefore the active area on the base wouldessentially be the mirror image of the cavity aperture on the basesurface, that is to say the area reflecting energy emerging from thephysical aperture of the cavity in the mask.

The mask 81 constructively occludes a portion of the optically activearea of the base with respect to the field of intended illumination. Inthe example of FIG. 6, the optically active area is the aperture 85 ofthe cavity 75; therefore the mask 81 occludes a substantial portion ofthe aperture 85, including the portion of the aperture on and about theaxis of the mask and cavity system. The surface of the mask 81 facingtowards the aperture 85 is reflective. Although it may be specular,typically this surface is diffusely reflective.

The relative dimensions of the mask 81 and aperture 85, for example therelative widths (or diameters or radii in a more circular system) aswell as the distance of the mask 81 away from the aperture 85, controlthe constructive occlusion performance characteristics of the lightingsystem 70. Certain combinations of these parameters produce a relativelyuniform emission intensity with respect to angles of emission, over awide portion of the field of view about the system axis (verticallydownward in FIG. 6), covered principally by the constructive occlusion.Other combinations of size and height result in a system performancethat is uniform with respect to a wide planar surface perpendicular tothe system axis at a fixed distance from the active area.

The shoulders 77, 79 also are reflective and therefore deflect at leastsome light downward. The shoulders (and side surfaces of the mask)provide additional optical processing of combined light from the cavity.The angles of the shoulders and the reflectivity of the surfaces thereoffacing toward the region to be illuminated by constructive occlusionalso contribute to the intensity distribution over that region. In theillustrated example, the reflective shoulders are horizontal, althoughthey may be angled somewhat downward from the plane of the aperture.

With respect to the energy of different wavelengths, the interior spaceformed between the cavity 75 and the facing surface of the mask 81operates as an optical integrating cavity, in essentially the samemanner as the integrating cavities in the previous embodiments. Again,the LEDs provide light of a number of different wavelengths, and thus ofdifferent colors in the visible spectrum. The optical cavity combinesthe light of multiple colors supplied from the LEDs 87. The controlcircuit 21 controls the amount of each color of light supplied to thechamber and thus the proportion thereof included in the combined outputlight. The constructive occlusion serves to distribute that light in adesired manner over a field or area that the system 70 is intended toilluminate, with a tailored intensity distribution.

The LEDs 87 could be located at (or coupled by optical fiber to emitlight) from any location or part of the surface of the cavity 75.Preferably, the LED outputs are not directly visible through theun-occluded portions of the aperture 85 (between the mask and the edgeof the cavity). In examples of the type shown in FIGS. 6 and 7, theeasiest way to so position the LED outputs is to mount the LEDs 87 (orprovide fibers or the like) so as to supply light to the chamber throughopenings through the mask 81.

FIG. 7 also provides an example of an arrangement of the LEDs in whichthere are both active and inactive (sleeper) LEDs of the various colors.As shown, the active part of the array of LEDs 87 includes two Red LEDs(R), one Green LED (G) and one Blue LED (B). The initially inactive partof the array of LEDs 87 includes two Red sleeper LEDs (RS), one Greensleeper LED (GS) and one Blue sleeper LED (BS). If other wavelengths orwhite light sources are desired, the apparatus may include an active LEDof the other color (O) as well as a sleeper LED of the other color (OS).The precise number, type, arrangement and mounting technique of the LEDsand the associated ports through the mask 81 are not critical. Thenumber of LEDs, for example, is chosen to provide a desired level ofoutput energy (intensity), for a given application.

The system 70 includes a control circuit 21 and power source 23. Theseelements control the operation and output intensity of each LED 87. Theindividual intensities determine the amount of each color light includedin the integrated and distributed output. The control circuit 21functions in essentially the same manner as in the other examples.

FIGS. 8 and 9 illustrate a second constructive occlusion example. Inthis example, the physical cavity is actually formed in the mask, andthe active area of the base is a flat reflective panel of the base.

The illustrated system 90 comprises a flat base panel 91, a mask 93, LEDlight sources 95, and a conical deflector 97. The system 90 iscircularly symmetrical about a vertical axis, although it could berectangular or have other shapes. The base 91 includes a flat centralregion 99 between the walls of the deflector 97. The region 99 isreflective and forms or contains the active optical area on the basefacing toward the region or area to be illuminated by the system 90.

The mask 93 is positioned between the base 91 and the region to beilluminated by constructive occlusion. For example, in the orientationshown, the mask 93 is above the active optical area 99 of the base 91,for example to direct light toward a ceiling for indirect illumination.Of course, the mask and cavity system could be inverted to serve as adownlight for task lighting applications, or the mask and cavity systemcould be oriented to emit light in directions appropriate for otherapplications.

In this example, the mask 93 contains the diffusely reflective cavity101, constructed in a manner similar to the integrating cavities in theearlier examples. The physical aperture 103 of the cavity 101 and of anydiffusely reflective surface(s) of the mask 93 that may surround thataperture form an active optical area on the mask 93. Such an active areaon the mask faces away from the region to be illuminated and toward theactive surface 99 on the base 91. The surface 99 is reflective,preferably with a diffuse characteristic. The surface 99 of the base 91essentially acts to produce a diffused mirror image of the mask 93 withits cavity 101 as projected onto the base area 99. The reflection formedby the active area of the base becomes the effective aperture of theoptical integrating cavity (between the mask and base) when the fixtureis considered from the perspective of the area of intended illumination.The surface area 99 reflects energy emerging from the aperture 103 ofthe cavity 101 in the mask 93. The mask 93 in turn constructivelyoccludes light diffused from the active base surface 99 with respect tothe region illuminated by the system 90. The dimensions and relativepositions of the mask and active region on the base control theperformance of the system, in essentially the same manner as in the maskand cavity system of FIGS. 6 and 7.

The system 90 includes a control circuit 21 and associated power source23, for supplying controlled electrical power to the LED sources 95. Inthis example, the LEDs emit light through openings through the base 91,preferably at points not directly visible from outside the system. TheLEDs 95 supply various wavelengths of light, and the circuit 21 controlsthe power of each LED, to control the amount of each color of light inthe combined output, as discussed above relative to the other examples.

The base 91 could have a flat ring-shaped shoulder with a reflectivesurface. In this example, however, the shoulder is angled toward thedesired field of illumination to form a conical deflector 97. The innersurface of the deflector 97 is reflective, as in the earlier examples.

The deflector 97 has the shape of a truncated cone, in this example,with a circular lateral cross section. The cone has two circularopenings. The cone tapers from the large end opening to the narrow endopening, which is coupled to the active area 99 of the base 91. Thenarrow end of the deflector cone receives light from the surface 99 andthus from diffuse reflections between the base and the mask.

The entire area of the inner surface of the cone 97 is reflective. Atleast a portion of the reflective surface is specular, as in thedeflectors of the earlier examples. The angle of the wall(s) of theconical deflector 97 substantially corresponds to the angle of thedesired field of view of the illumination intended for the system 90.Because of the reflectivity of the wall of the cone 97, most if not allof the light reflected by the inner surface thereof would at leastachieve an angle that keeps the light within the field of view.

The LED light sources 95 emit multiple wavelengths of light into themask cavity 101. The light sources 95 may direct some light toward theinner surface of the deflector 97. Light rays impacting on the diffuselyreflective surfaces, particularly those on the inner surface of thecavity 101 and the facing surface 99 of the base 91, reflect and diffuseone or more times within the confines of the system and emerge throughthe gap between the perimeter of the active area 99 of the base and theouter edge of the mask 93. The mask cavity 101 and the base surface 99function as an optical integrating cavity with respect to the light ofvarious wavelengths, and the gap becomes the actual integrating cavityaperture from which combined light emerges. The light emitted throughthe gap and/or reflected from the surface of the inner surface of thedeflector 97 irradiates a region (upward in the illustrated orientation)with a desired intensity distribution and with a desired spectralcharacteristic, essentially as in the earlier examples.

Additional information regarding constructive occlusion based systemsfor generating and distributing radiant energy may be found in commonlyassigned U.S. Pat. Nos. 6,342,695, 6,334,700, 6,286,979, 6,266,136 and6,238,077. The color integration principles discussed herein may beadapted to any of the constructive occlusion devices discussed in thosepatents.

The inventive devices have numerous applications, and the outputintensity and spectral characteristic may be tailored and/or adjusted tosuit the particular application. For example, the intensity of theintegrated radiant energy emitted through the aperture may be at a levelfor use in a rumination application or at a level sufficient for a tasklighting application. A number of other control circuit features alsomay be implemented. For example, the control may maintain a set colorcharacteristic in response to feedback from a color sensor. The controlcircuitry may also include a temperature sensor. In such an example, thelogic circuitry is also responsive to the sensed thermal temperature,e.g. to reduce intensity of the source outputs to compensate fortemperature increases while maintaining a set color characteristic. Thecontrol circuitry may include an appropriate device for manually settingthe desired spectral characteristic, for example, one or more variableresistors or one or more dip switches, to allow a user to define orselect the desired color distribution.

Automatic controls also are envisioned. For example, the controlcircuitry may include a data interface coupled to the logic circuitry,for receiving data defining the desired color distribution. Such aninterface would allow input of control data from a separate or evenremote device, such as a personal computer, personal digital assistantor the like. A number of the devices, with such data interfaces, may becontrolled from a common central location or device. Automatic receptionor sensing of information, to obtain setting data, also is encompassedby the present teachings. The light settings are easily recorded andreused at a later time or even at a different location using a differentsystem.

To appreciate the features and examples of the control circuitryoutlined above, it may be helpful to consider specific examples withreference to appropriate diagrams.

FIG. 10 is a block diagram of exemplary circuitry for the sources andassociated control circuit, providing digital programmable control,which may be utilized with a light integrating fixture of the typedescribed above. In this circuit example, the sources of radiant energyof the various types takes the form of an LED array 111. The array 111comprises two or more LEDs of each of the three primary colors, redgreen and blue, represented by LED blocks 113, 115 and 117. For example,the array may comprise six red LEDs 113, three green LEDs 115 and threeblue LEDs 117.

The LED array in this example also includes a number of additional or“other” LEDs 119. There are several types of additional LEDs that are ofparticular interest in the present discussion. One type of additionalLED provides one or more additional wavelengths of radiant energy forintegration within the chamber. The additional wavelengths may be in thevisible portion of the light spectrum, to allow a greater degree ofcolor adjustment.

The second type of additional LED that may be included in the system isa sleeper LED. As discussed above, some LEDs would be active, whereasthe sleepers would be inactive, at least during initial operation. Usingthe circuitry of FIG. 10 as an example, the Red LEDs 113, Green LEDs 115and Blue LEDs 117 might normally be active. The LEDs 119 would besleeper LEDs, typically including one or more LEDs of each color used inthe particular system.

The third type of other LED of interest is a white LED. For whitelighting applications, one or more white LEDs provide increasedintensity. The primary color LEDs then provide light for coloradjustment and/or correction to achieve a desired color temperature andΔUV.

The electrical components shown in FIG. 10 also include an LED controlsystem 120. The system 120 includes driver circuits for the various LEDsand a microcontroller. The driver circuits supply electrical current tothe respective LEDs 113 to 119 to cause the LEDs to emit light. Thedriver circuit 121 drives the Red LEDs 113, the driver circuit 123drives the green LEDs 115, and the driver circuit 125 drives the BlueLEDs 117. In a similar fashion, when active, the driver circuit 127provides electrical current to the other LEDs 119. If the other LEDsprovide another color of light, and are connected in series, there maybe a single driver circuit 127. If the LEDs are sleepers, it may bedesirable to provide a separate driver circuit 127 for each of the LEDs119. The intensity of the emitted light of a given LED is proportionalto the level of current supplied by the respective driver circuit.

The current output of each driver circuit is controlled by the higherlevel logic of the system. In this digital control example, that logicis implemented by a programmable microcontroller 129, although thoseskilled in the art will recognize that the logic could take other forms,such as discrete logic components, an application specific integratedcircuit (ASIC), etc.

The LED driver circuits and the microcontroller 129 receive power from apower supply 131, which is connected to an appropriate power source (notseparately shown). For most illumination applications, the power sourcewill be an AC line current source, however, some applications mayutilize DC power from a battery or the like. The power supply 129converts the voltage and current from the source to the levels needed bythe driver circuits 121-127 and the microcontroller 129.

A programmable microcontroller typically includes or has coupled theretorandom-access memory (RAM) for storing data and read-only memory (ROM)and/or electrically erasable read only memory (EEROM) for storingcontrol programming and any pre-defined operational parameters, such aspre-established light ‘recipes.’ The microcontroller 129 itselfcomprises registers and other components for implementing a centralprocessing unit (CPU) and possibly an associated arithmetic logic unit.The CPU implements the program to process data in the desired manner andthereby generate desired control outputs.

The microcontroller 129 is programmed to control the LED driver circuits121-127 to set the individual output intensities of the LEDs to desiredlevels, so that the combined light emitted from the aperture of thecavity has a desired spectral characteristic and a desired overallintensity. The microcontroller 129 may be programmed to essentiallyestablish and maintain or preset a desired ‘recipe’ or mixture of theavailable wavelengths provided by the LEDs used in the particular systemto provide desired illumination of an identified subject. Themicrocontroller 129 receives control inputs specifying the particular‘recipe’ or mixture, as will be discussed below. To insure that thedesired mixture is maintained, the microcontroller receives a colorfeedback signal from an appropriate color sensor. The microcontrollermay also be responsive to a feedback signal from a temperature sensor,for example, in or near the optical integrating cavity.

The electrical system will also include one or more control inputs 133for inputting information instructing the microcontroller 129 as to thedesired operational settings. A number of different types of inputs maybe used, and several alternatives are illustrated for convenience. Agiven installation may include a selected one or more of the settingdata input mechanisms.

As one example, user inputs may take the form of a number ofpotentiometers 135. The number would typically correspond to the numberof different light wavelengths provided by the particular LED array 111.The potentiometers 135 typically connect through one or more analog todigital conversion interfaces provided by the microcontroller 129 (or inassociated circuitry). To set the parameters for the integrated lightoutput, the user adjusts the potentiometers 135 to set the intensity foreach color. The microcontroller 129 senses the input settings andcontrols the LED driver circuits accordingly, to set correspondingintensity levels for the LEDs providing the light of the variouswavelengths.

Another user input implementation might utilize one or more dip switches137. For example, there might be a series of such switches to input acode corresponding to one of a number of recipes. The memory used by themicrocontroller 129 would store the necessary intensity levels for thedifferent color LEDs in the array 111 for each recipe. Based on theinput code, the microcontroller 129 retrieves the appropriate recipefrom memory. Then, the microcontroller 129 controls the LED drivercircuits 121-127 accordingly, to set corresponding intensity levels forthe LEDs 113-119 providing the light of the various wavelengths.

As an alternative or in addition to the user input in the form ofpotentiometers 135 or dip switches 137, the microcontroller 129 may beresponsive to control data supplied from a separate source or a remotesource. For that purpose, some versions of the system will include oneor more communication interfaces. One example of a general class of suchinterfaces is a wired interface 139. One type of wired interfacetypically enables communications to and/or from a personal computer orthe like, typically within the premises in which the fixture operates.Examples of such local wired interfaces include USB, RS-232, andwire-type local area network (LAN) interfaces. Other wired interfaces,such as appropriate modems, might enable cable or telephone linecommunications with a remote computer, typically outside the premises.Other examples of data interfaces provide wireless communications, asrepresented by the interface 141 in the drawing. Wireless interfaces,for example, use radio frequency (RF) or infrared (IR) links. Thewireless communications may be local on-premises communications,analogous to a wireless local area network (WLAN). Alternatively, thewireless communications may enable communication with a remote deviceoutside the premises, using wireless links to a wide area network.

The automatic inputs allow communication from any of a variety of otherequipment, to input one or more of the color “recipes.” Those skilled inthe art will understand that these interfaces also enable the system toreceive identifiers corresponding to subjects to be illuminated, for usein selecting and applying the appropriate stored recipe. Theseinterfaces may also enable the system to receive, store and applysettings automatically, e.g. from RFID tags or bar codes on products,packages, business cards, or the like.

As noted above, the electrical components may also include one or morefeedback sensors 143, to provide system performance measurements asfeedback signals to the control logic, implemented in this example bythe microcontroller 129. A variety of different sensors may be used,alone or in combination, for different applications. In the illustratedexamples, the set 143 of feedback sensors includes a color sensor 145and a thermal temperature sensor 147. Although not shown, other sensors,such as an overall intensity sensor may be used. The sensors arepositioned in or around the system to measure the appropriate physicalcondition, e.g. temperature, color, intensity, etc.

The color sensor 145, for example, is coupled to detect colordistribution in the integrated radiant energy. The color sensor may becoupled to sense energy within the optical integrating cavity, withinthe deflector (if provided) or at a point in the field illuminated bythe particular system. If some small amount of the integrated lightpasses through a point on a wall of the cavity, it may be sufficient tosense color at that point on the cavity wall. Various examples ofappropriate color sensors are known. For example, the color sensor maybe a digital compatible sensor, of the type sold by TAOS, Inc. Anothersuitable sensor might use the quadrant light detector disclosed in U.S.Pat. No. 5,877,490, with appropriate color separation on the variouslight detector elements (see U.S. Pat. No. 5,914,487 for discussion ofthe color analysis).

The associated logic circuitry, responsive to the detected colordistribution, controls the output intensity of the various LEDs, so asto provide a desired color distribution in the integrated radiantenergy, in accord with appropriate settings. In an example using sleeperLEDs, the logic circuitry is responsive to the detected colordistribution to selectively activate the inactive light emitting diodesas needed, to maintain the desired color distribution in the integratedradiant energy. The color sensor measures the color of the integratedradiant energy produced by the system and provides a color measurementsignal to the microcontroller 129. If using the TAOS, Inc. color sensor,for example, the signal is a digital signal derived from a color tofrequency conversion.

The thermal temperature sensor 147 may be a simple thermoelectrictransducer with an associated analog to digital converter, or a varietyof other temperature detectors may be used. The temperature sensor ispositioned on or inside of the fixture, typically at a point that isnear the LEDs or other sources that produce most of the system heat. Thetemperature sensor 147 provides a signal representing the measuredtemperature to the microcontroller 129. The system logic, hereimplemented by the microcontroller 129, can adjust intensity of one ormore of the LEDs in response to the sensed temperature, e.g. to reduceintensity of the source outputs to compensate for temperature increases.The program of the microcontroller 129, however, would typicallymanipulate the intensities of the various LEDs so as to maintain thedesired color balance between the various wavelengths of light used inthe system, even though it may vary the overall intensity withtemperature. For example, if temperature is increasing due to increaseddrive current to the active LEDs (with increased age or heat), thecontroller may deactivate one or more of those LEDs and activate acorresponding number of the sleepers, since the newly activatedsleeper(s) will provide similar output in response to lower current andthus produce less heat.

The above discussion of FIG. 10 related to programmed digitalimplementations of the control logic. Those skilled in the art willrecognize that the control also may be implemented using analogcircuitry. FIG. 11 is a circuit diagram of a simple analog control for alighting apparatus (e.g. of the type shown in FIG. 1) using Red, Greenand Blue LEDs. The user establishes the levels of intensity for eachtype of radiant energy emission (Red, Green or Blue) by operating acorresponding one of the potentiometers. The circuitry essentiallycomprises driver circuits for supplying adjustable power to two or threesets of LEDs (Red, Green and Blue) and analog logic circuitry foradjusting the output of each driver circuit in accord with the settingof a corresponding potentiometer. Additional potentiometers andassociated circuits would be provided for additional colors of LEDs.Those skilled in the art should be able to implement the illustratedanalog driver and control logic of FIG. 11 without further discussion.

Some lighting applications involve a common overall control strategy fora number of the systems. As noted in the discussion of FIG. 10, thecontrol circuitry may include a communication interface 139 or 141allowing the microcontroller 129 to communicate with another processingsystem. FIG. 12 illustrates an example in which control circuits 21 of anumber of the radiant energy generation systems with the lightintegrating and distribution type fixture communicate with a mastercontrol unit 151 via a communication network 153. The master controlunit 151 typically is a programmable computer with an appropriate userinterface, such as a personal computer or the like. The communicationnetwork 153 may be a LAN or a wide area network, of any desired type.The communications allow an operator to control the color and outputintensity of all of the linked systems, for example to provide combinedlighting effects or to control lighting of a large product display. Thecommonly controlled lighting systems may be arranged in a variety ofdifferent ways, depending on the intended use of the systems.

The systems described above have a wide range of applications, wherethere is a desire to set or adjust color provided by a lighting fixture.Applications may include task lighting, however, applications ofparticular interest relate to illuminating an object or person in amanner that provides precise control and repeatability of the spectral(color) characteristics of the illumination.

FIG. 13 illustrates another example of a “lighting” system 260 with anoptical integrating cavity LED light fixture, having yet other elementsto optically process the combined color light output, e.g. for stage orstudio illumination. The system 260 includes an optical integratingcavity and LEDs similar to the example of FIG. 1, and like referencenumerals are used to identify the corresponding components.

In the example of FIG. 13, the light fixture includes an opticalintegrating cavity 11, formed by a dome 11 and a cover plate 15. Thesurfaces of the dome 13 and cover 15 forming the interior surface(s) ofthe cavity 11 are diffusely reflective. One or more apertures 17, inthis example formed through the plate 15, provide a light passage fortransmission of reflected and integrated light outward from the cavity11. Materials, possible shapes, positions and orientations for theelements 11 to 17 have been discussed above. As in the earlier examples,the system 260 includes a number of LEDs 19 emitting light of differentwavelengths into the cavity 11. The possible combinations and positionsof the LEDs 19 have been discussed in detail above, in relation to theearlier examples.

The LEDs 19 emit light of multiple light colors in the visible portionof the radiant energy spectrum into the interior of the opticalintegrating cavity 11. Control of the amplitudes of the drive currentsapplied to the LEDs 19 controls the amount of each light color suppliedinto the cavity 11. A number of the LEDs will be active, from initialstart-up, whereas others may initially be inactive ‘sleepers,’ asdiscussed above. The cavity 11 integrates the various amounts of lightof the different colors into a combined light of a desired colortemperature for emission through the aperture 17.

The system 260 also includes a control circuit 262 coupled to the LEDs19 for establishing output intensity of radiant energy of each of theLED sources. The control circuit 262 typically includes a power supplycircuit coupled to a source, shown as an AC power source 264, althoughthe power source 264 may be a DC power source. In either case, thecircuit 262 may be adapted to process the voltage from the availablesource to produce the drive currents necessary for the LEDs 19. Thecontrol circuit 262 includes an appropriate number of LED drivercircuits, as discussed above relative to FIGS. 10 and 11, forcontrolling the power applied to each of the individual LEDs 19 and thusthe intensity of radiant energy supplied to the cavity 11 for eachdifferent type/color of light. Control of the intensity of emission ofeach of the LED sources sets a spectral characteristic of the combinedradiant energy emitted through the aperture 17 of the opticalintegrating cavity 11, in this case, the color characteristic(s) of thevisible light output.

The control circuit 262 may respond to a number of different inputsignals representing color characteristic settings, for example, asshown by the arrow in FIG. 16. Feedback may also be provided by atemperature sensor (not shown in this example) or one or more colorsensors 266. The color sensor(s) 266 may be located in the cavity or inthe element or elements for processing light emitted through theaperture 17. However, in many cases, the plate 15 and/or dome 13 maypass some of the integrated light from the cavity, in which case, it isactually sufficient to place the color light sensor(s) 266 adjacent anysuch transmissive point on the outer wall that forms the cavity. In theexample, the sensor 266 is shown attached to the plate 15. Details ofthe control feedback have been discussed earlier, with regard to thecircuitry in FIG. 10.

The example of FIG. 13 utilizes a different arrangement for directingand processing the light after emission from the cavity 11 through theaperture 17. This system 260 utilizes a collimator 253, an adjustableiris 255 and an adjustable focus lens system 259.

The collimator 253 may have a variety of different shapes, depending onthe desired application and the attendant shape of the aperture 17. Forease of discussion here, it is assumed that the elements shown arecircular, including the aperture 17. Hence, in the example, thecollimator 253 comprises a substantially cylindrical tube, having acircular opening at a proximal end coupled to the aperture 17 of theoptical integrating cavity 11. The system 260 emits light toward adesired field of illumination via the circular opening at the distal endof the collimator 253.

The interior surface of the collimator 253 is reflective. The reflectiveinner surface may be diffusely reflective or quasi-specular. Typically,in this embodiment, the interior surface of the deflector/collimatorelement 253 is specular. The tube forming the collimator 253 alsosupports a series of elements for optically processing the collimatedand integrated light. Those skilled in the art will be familiar with thetypes of processing elements that may be used, but for purposes ofunderstanding, it may be helpful to consider two specific types of suchelements.

First, the tube forming the collimator 253 supports a variable iris. Theiris 257 represents a secondary aperture, which effectively limits theoutput opening and thus the intensity of light that may be output by thesystem 260. Although shown in the collimator tube, the iris may bemounted in or serve as the aperture 17. A circuit 257 controls the sizeor adjustment of the opening of the iris 255. In practice, the useractivates the LED control circuit (see e.g. 21 in FIG. 1) to set thecharacteristic (e.g. color temperature and ΔUV) of the output light,that is to say, so that the system 260 outputs light of a colorcharacteristic desired for illumination of a particular subject. Theoverall intensity of the output light is then controlled through thecircuit 257 and the iris 255. Opening the iris 255 wider provides higheroutput intensity, whereas reducing the iris opening size decreasesintensity of the light output.

In the system 260, the tube forming the collimator 253 also supports oneor more lens elements of the adjustable focusing system 259, shown byway of example as two lenses 261 and 263. Spacing between the lensesand/or other parameters of the lens system 259 are adjusted by amechanism 265, in response to a signal from a focus control circuit 267.The elements 261 to 267 of the system 259 are shown here by way ofexample, to represent a broad class of elements that may be used tovariably focus the emitted light in response to a control signal ordigital control information or the like. If the system 260 serves as aspot light, adjustment of the lens system 259 effectively controls thesize of the spot on the person or other target object that the systemilluminates. Those skilled in the art will recognize that other opticalprocessing elements may be provided, such as a mask to control the shapeof the illumination spot or various shutter arrangements for beamshaping.

Although shown as separate control circuits 257 and 267, the functionsof these circuits may be integrated together with each other orintegrated into the circuit 262 that controls the operation of the LEDs19. For example, the system might use a single microprocessor or similarprogrammable microcontroller, which would run control programs for theLED drive currents, the iris control and the focus control.

The optical integrating cavity 11 and the LEDs 19 produce light of aprecisely controlled composite color. As noted, control of the LEDcurrents controls the amount of each color of light integrated into theoutput and thus the output light color. Control of the opening providedby the iris 255 then controls the intensity of the integrated lightoutput of the system 260. Control of the focusing by the system 259enables control of the breadth of the light emissions and thus thespread of the area or region to be illuminated by the system 260. Otherelements may be provided to control beam shape. Professional productionlighting applications for such a system include theater or studiolighting, for example, where it is desirable to control the color,intensity and the size of a spotlight beam. By connecting the LEDcontrol circuit 257, the iris control circuit 257 and the focus controlcircuit 267 to a network similar to that in FIG. 12, it becomes possibleto control color, intensity and spot size from a remote networkterminal, for example, at an engineer's station in the studio ortheater.

FIGS. 14 and 15 show another fixture, but here adapted for use as a“wall-washer” illuminant lighting fixture. The fixture 330 includes anoptical integrating cavity 331 having a diffusely reflective innersurface, as in the earlier examples. In this fixture, the cavity 331again has a substantially rectangular cross-section. FIG. 15 is anisometric view of a section of the fixture, showing several of thecomponents formed as a single extrusion of the desired cross section,but without any end-caps.

As shown in these figures, the fixture 330 includes severalinitially-active LEDs and several sleeper LEDs, generally shown at 339,similar to those in the earlier examples. The LEDs emit controlledamounts of multiple colors of light into the optical integrating cavity341 formed by the inner surfaces of a rectangular member 333. A powersource and control circuit similar to those used in the earlier examplesprovide the drive currents for the LEDs 339, and in view of thesimilarity, the power source and control circuit are omitted from FIG.21, to simplify the illustration. One or more apertures 337, of theshape desired to facilitate the particular lighting application, providelight passage for transmission of reflected and integrated light outwardfrom the cavity 341. Materials for construction of the cavity and thetypes of LEDs that may be used are similar to those discussed relativeto the earlier illumination examples, although the number andintensities of the LEDs may be different, to achieve the outputparameters desired for the particular wall-washer application.

The fixture 330 in this example (FIG. 14) includes a deflector tofurther process and direct the light emitted from the aperture 337 ofthe optical integrating cavity 341, in this case toward a wall, productor other subject somewhat to the left of and above the fixture 330. Thedeflector is formed by two opposing panels 345 a and 345 b of theextruded body of the fixture. The panel 345 a is relatively flat andangled somewhat to the left, in the illustrated orientation. Assuming avertical orientation of the fixture as shown in FIG. 21, the panel 345 bextends vertically upward from the edge of the aperture 337 and is bentback at about 90°. The shapes and angles of the panels 345 a and 345 bare chosen to direct the light to a particular area of a wall or productdisplay that is to be illuminated, and may vary from application toapplication.

Each panel 345 a, 345 b has a reflective interior surface 349 a, 349 b.As in the earlier examples, all or portions of the deflector surfacesmay be diffusely reflective, quasi-specular or specular. In the wallwasher example, the deflector panel surface 349 b is diffuselyreflective, and the deflector panel surface 349 a has a specularreflectivity, to optimize distribution of emitted light over the desiredarea illuminated by the fixture 330.

The output opening of the deflector 345 may be covered with a grating, aplate or lens, although in the illustrated wall washer example, such anelement is omitted.

FIG. 16 is a cross sectional view of another example of a wall washertype fixture 350. The fixture 350 includes an optical integrating cavity351 having a diffusely reflective inner surface, as in the earlierexamples. In this fixture, the cavity 351 again has a substantiallyrectangular cross-section. As shown, the fixture 350 includes at leastone white light source, represented by the white LED 355. The fixturealso includes several LEDs 359 of the various primary colors, typicallyred (R), green (G) and blue (B, not visible in this cross-sectionalview). The LEDs 359 include both initially-active LEDs and sleeper LEDs,and the LEDs 359 are similar to those in the earlier examples. Again,the LEDs emit controlled amounts of multiple colors of light into theoptical integrating cavity 351 formed by the inner surfaces of arectangular member 353. A power source and control circuit similar tothose used in the earlier examples provide the drive currents for theLEDs 359, and in this example, that same circuit controls the drivecurrent applied to the white LED 355. In view of the similarity, thepower source and control circuit are omitted from FIG. 16, to simplifythe illustration.

One or more apertures 357, of the shape desired to facilitate theparticular lighting application, provide light passage for transmissionof reflected and integrated light outward from the cavity 351. Theaperture may be laterally centered, as in the earlier examples; however,in this example, the aperture is off-center to facilitate alight-through to the left (in the illustrated orientation). Materialsfor construction of the cavity and the types of LEDs that may be usedare similar to those discussed relative to the earlier illuminationexamples.

Here, it is assumed that the fixture 350 is intended to principallyprovide white light, for example, to illuminate a wall or product to theleft and somewhat above the fixture. The presence of the white lightsource 355 increases the intensity of white light that the fixtureproduces. The control of the outputs of the primary color LEDs 359allows the operator to adjust the color characteristics of the whitelight output, typically for desired illumination of different subjects.

As an example of operation, the fixture 350 may be used to illuminateproducts, e.g. as displayed in a store or the like, although it may berotated or inverted for such a use. Different products may present abetter impression if illuminated by white light having a colortemperature and ΔUV. For example, fresh bananas may be more attractiveto a potential customer when illuminated by light having more yellowtones. Soda sold in red cans, however, may be more attractive to apotential customer when illuminated by light having more red tones. Foreach product, the user can adjust the intensities of the light outputsfrom the LEDs 359 and/or 355 to produce light that appears substantiallywhite if observed directly by a human/customer but provides the desiredhighlighting tones and thereby optimizes lighting of the particularproduct that is on display.

The fixture 350 may have any desired output processing element(s), asdiscussed above with regard to various earlier examples. In theillustrated wall washer embodiment (FIG. 16), the fixture 350 includes adeflector to further process and direct the light emitted from theaperture 357 of the optical integrating cavity 351, in this case towarda wall or product somewhat to the left of and above the fixture 350. Thedeflector is formed by two opposing panels 365 a and 365 b havingreflective inner surfaces 365 a and 365 b. Although other shapes may beused to direct the light output to the desired area or region, theillustration shows the panel 365 a, 365 b as relatively flat panels setat somewhat different angle extending to the left, in the illustratedorientation. Of course, as for all the examples, the fixture may beturned at any desired angle or orientation to direct the light to aparticular region or object to be illuminated by the fixture, in a givenapplication.

As noted, each panel 365 a, 365 b has a reflective interior surface 369a, 369 b. As in the earlier examples, all or portions of the deflectorsurfaces may be diffusely reflective, quasi-specular or specular. In thewall washer example, the deflector panel surface 369 b is diffuselyreflective, and the deflector panel surface 369 a has a specularreflectivity, to optimize distribution of emitted light over the desiredarea of the wall illuminated by the fixture 350. The output opening ofthe deflector 365 may be covered with a grating, a plate or lens,although in the illustrated wall washer example, such an element isomitted.

FIG. 17 is a cross-sectional view of another example of an opticalintegrating cavity type light fixture 370. This example uses a deflectorand lens to optically process the light output, and like the example ofFIG. 16 the fixture 370 includes LEDs to produce various colors of lightin combination with a white light source. The fixture 370 includes anoptical integrating cavity 371, formed by a dome and a cover plate,although other structures may be used to form the cavity. The surfacesof the dome and cover forming the interior surface(s) of the cavity 371are diffusely reflective. One or more apertures 377, in this exampleformed through the cover plate, provide a light passage for transmissionof reflected and integrated light outward from the cavity 371.Materials, sizes, orientation, positions and possible shapes for theelements forming the cavity and the types/numbers of LEDs have beendiscussed above.

As shown, the fixture 370 includes at least one white light source.Although the white light source could comprise one or more LEDs, as inthe previous example (FIG. 16), in this embodiment, the white lightsource comprises a lamp 375. The lamp may be any convenient form oflight bulb, such as an incandescent or fluorescent light bulb; and theremay be one, two or more bulbs to produce a desired amount of whitelight. A preferred example of the lamp 375 is a quartz halogen lightbulb. The fixture also includes several LEDs 379 of the various primarycolors, typically red (R), green (G) and blue (B, not visible in thiscross-sectional view), although additional colors may be provided orother color LEDs may be substituted for the RGB LEDs. Some LEDs will beactive from initial operation. Other LEDs may be held in reserve assleepers. The LEDs 379 are similar to those in the earlier examples, foremitting controlled amounts of multiple colors of light into the opticalintegrating cavity 371.

A power source and control circuit similar to those used in the earlierexamples provide the drive currents for the LEDs 359. In view of thesimilarity, the power source and control circuit for the LEDs areomitted from FIG. 17, to simplify the illustration. The lamp 375 may becontrolled by the same or similar circuitry, or the lamp may have afixed power source.

The white light source 375 may be positioned at a point that is notdirectly visible through the aperture 377 similar to the positions ofthe LEDs 379. However, for applications requiring relatively high whitelight output intensity, it may be preferable to position the white lightsource 375 to emit a substantial portion of its light output directlythrough the aperture 377.

The fixture 370 may incorporate any of the further optical processingelements discussed above. For example, the fixture may include avariable iris and variable focus system, as in the embodiment of FIG.13. In the illustrated version, however, the fixture 370 includes adeflector 385 to further process and direct the light emitted from theaperture 377 of the optical integrating cavity 371. The deflector 385has a reflective interior surface 389 and expands outward laterally fromthe aperture, as it extends away from the cavity toward the region to beilluminated. In a circular implementation, the deflector 385 would beconical. Of course, for applications using other fixture shapes, thedeflector may be formed by two or more panels of desired sizes andshapes. The interior surface 389 of the deflector 385 is reflective. Asin the earlier examples, all or portions of the reflective deflectorsurface(s) may be diffusely reflective, quasi-specular, specular orcombinations thereof.

As shown in FIG. 17, a small opening at a proximal end of the deflector385 is coupled to the aperture 377 of the optical integrating cavity311. The deflector 385 has a larger opening at a distal end thereof. Theangle of the interior surface 389 and size of the distal opening of thedeflector 385 define an angular field of radiant energy emission fromthe apparatus 370.

The large opening of the deflector 385 is covered with a grating, aplate or the exemplary lens 387. The lens 387 may be clear ortranslucent to provide a diffuse transmissive processing of the lightpassing out of the large opening. Prismatic materials, such as a sheetof microprism plastic or glass also may be used. In applications where aperson may look directly at the fixture 370 from the illuminated region,it is preferable to use a translucent material for the lens 387, toshield the observer from directly viewing the lamp 375.

The fixture 370 thus includes a deflector 385 and lens 387, for opticalprocessing of the integrated light emerging from the cavity 371 via theaperture 377. Of course, other optical processing elements may be usedin place of or in combination with the deflector 385 and/or the lens387.

In the fixture of FIG. 17, the lamp 375 provides substantially whitelight of relatively high intensity. Hence, most of the light outputexhibits spectral characteristics of the lamp 375. The integration ofthe light from the LEDs 379 in the cavity 375 supplements the light fromthe lamp 375 with additional colors, and the amounts of the differentcolors of light from the LEDs can be precisely controlled. Control ofthe light added from the LEDs can provide color correction (e.g. for ageor variation of the lamp) and color adjustment for desired settings, asdiscussed above relative to the embodiment of FIG. 16.

The exemplary systems discussed herein may have any size desirable forany particular application. A system may be relatively large, forlighting a room or product display or for providing spot or floodlighting. The system also may be relatively small, for example, toprovide a small pinpoint of light. The system is particularly amenableto miniaturization. For example, instead of a plate to support the LEDs,the LEDs could be manufactured on a single chip. For some applications,it may also be desirable to form the integrating cavity on the chip oras part of the semiconductor package.

As shown by the discussion above, each of the various radiant energyemission systems with multiple color sources and an optical cavity tocombine the energy from the sources provides a highly effective means tocontrol the color produced by one or more fixtures. The output colorcharacteristics are controlled simply by controlling the intensity ofeach of the sources supplying radiant energy to the chamber. The controlof input intensity of the different wavelengths or colors of lightsprovides precise repeatable control of the combined light output.Settings to provide desired illumination of a particular subject, e.g. adesired white color temperature and difference from the black bodycurve, can be easily reused, transferred and/or replicated, whenever andwherever it is desired to illuminate the exact same subject or anotherinstance of that subject.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that they may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim any and allmodifications and variations that fall within the true scope of thepresent concepts.

1. A method of illuminating a subject, comprising: generating a variableamount of light of a first wavelength and a variable amount of light ofa second wavelength, wherein the second wavelength is different from thefirst wavelength; optically combining the light of the first wavelengthwith the light of the second wavelength; illuminating the subject withthe combined light; adjusting at least one of the amount of the lightand the first wavelength or the amount of the light of the secondwavelength, to achieve a color characteristic of a desired illuminationof the subject with the combined light; recording the amount of thelight of the first wavelength and the amount of the light of the secondwavelength contained in the combined light used to achieve the desiredillumination of the subject; setting a lighting system to generate therecorded amount of the light of the first wavelength and to generate therecorded amount of the light of the second wavelength; operating thelighting system to generate the set recorded amounts of light of thefirst and second wavelengths; during operation of the lighting system,measuring a temperature condition associated with operation of thelighting system; optically combining the light of the first and secondwavelengths generated by the lighting system to produce a combined lightoutput corresponding to the desired illumination, and based on themeasured temperature condition; and irradiating the subject with thecombined light output from the lighting system, to achieve the desiredillumination of the subject using the lighting system.
 2. The methodaccording to claim 1, wherein the step of operating further comprises:adjusting intensity of the amount of the light of the first wavelengthor the amount of the light of the second wavelength in response to themeasured temperature condition.
 3. The method according to claim 1,wherein the measuring step includes: sensing a temperature of one ormore light emitting diodes producing the first or second wavelengthlight positioned inside the lighting system.
 4. The method according toclaim 3, further comprising: reducing an intensity of light generated byone or more of the light emitting diodes in response to the measuredtemperature condition of the one or more light emitting diodes tocompensate for an increased temperature inside the lighting system. 5.The method according to claim 3, further comprising: increasing anintensity of light generated by one or more of the light emitting diodesin response to the measured temperature condition of the one or morelight emitting diodes to compensate for a decreased temperature insidethe lighting system.
 6. The method according to claim 3, furthercomprising the step of: deactivating one or more of the light emittingdiodes.
 7. The method according to claim 6, further comprising the stepof: activating one or more corresponding light emitting diodes toproduce a similar light wavelength produced by the deactivated lightemitting diode.
 8. The method according to claim 1, wherein themeasuring step includes: measuring the temperature condition inside thelighting system.
 9. The method according to claim 1, wherein themeasuring step includes: measuring the temperature condition around thelighting system.
 10. A method of illuminating a subject with light of adesired color characteristic, comprising: setting a first amount forlight of a first wavelength; generating light of the first wavelengthfrom a first source, in a first intensity corresponding to the first setamount; setting a second amount for light of a second wavelength;generating light of the second wavelength from a second source, in asecond intensity corresponding to the second set amount, wherein thesecond wavelength is different from the first wavelength, and the firstand second set amounts correspond to the desired color characteristicfor the illumination of the subject; during generation of light of thefirst and second wavelengths, measuring a temperature conditionassociated with operation of the first and second sources; adjusting atleast one of the first intensity of the first source and the secondintensity of the second source in response to the measured temperaturecondition; diffusely reflecting the generated light of the first andsecond wavelengths from the first and second sources within a cavity, toproduce combined light containing amounts of light of the first andsecond wavelengths in proportion to the first and second set amounts;and emitting at least a portion of the combined light through anaperture of the cavity to illuminate the subject with light of thedesired color characteristic.
 11. The method of claim 10, wherein theadjusting step comprises: maintaining the desired color characteristicof the emitted combined light through the aperture.
 12. A method,comprising steps of: generating a variable amount of light of a firstwavelength and a variable amount of light of a second wavelength,wherein the second wavelength is different from the first wavelength;optically combining the light of the first wavelength with the light ofthe second wavelength to produce illumination with the combined light;adjusting at least one of the amount of the light of the firstwavelength and the amount of the light of the second wavelength, toachieve a desired color characteristic of the illumination with thecombined light; recording the amount of the light of the firstwavelength and the amount of the light of the second wavelengthcontained in the combined light used to achieve the desired colorcharacteristic of the illumination; setting a lighting system togenerate the recorded amount of the light of the first wavelength and togenerate the recorded amount of the light of the second wavelength;operating the lighting system to generate the set recorded amounts oflight of the first and second wavelengths; during operation of thelighting system, measuring a temperature associated with operation ofthe lighting system and adjusting generation of light of at least one ofthe first and second wavelengths based on the measured temperaturecondition; optically combining the light of the first and secondwavelengths generated by the lighting system to produce a combined lightoutput of the lighting system corresponding to the desired the desiredcolor characteristic; and emitting the combined light output asillumination from the lighting system.
 13. The method according to claim12, wherein the step of operating further comprises: adjusting intensityof the amount of the light of the first wavelength or the amount of thelight of the second wavelength in response to the measured temperaturecondition.
 14. The method according to claim 12, wherein the measuringstep includes: sensing a temperature of one or more light emittingdiodes producing the first or second wavelength light positioned insidethe lighting system.
 15. A method, comprising steps of: setting a firstamount for light of a first wavelength; generating light of the firstwavelength from a first source, in a first intensity corresponding tothe first set amount; setting a second amount for light of a secondwavelength; generating light of the second wavelength from a secondsource, in a second intensity corresponding to the second set amount,wherein the second wavelength is different from the first wavelength,and the first and second set amounts correspond to a desired colorcharacteristic; during generation of light of the first and secondwavelengths, measuring a temperature condition associated with operationthe first and second sources; adjusting at least one of the firstintensity of the first source and the second intensity of the secondsource in response to the measured temperature condition; diffuselyreflecting the generated light of the first and second wavelengths fromthe first and second sources within a cavity, to produce combined lightcontaining amounts of light of the first and second wavelengths inproportion to the first and second set amounts; and emitting at least aportion of the combined light through an aperture of the cavity forillumination with light of the desired color characteristic.
 16. Themethod according to claim 15, wherein the measuring step includes:sensing a temperature of one or more light emitting diodes producing thefirst or second wavelength light.
 17. The method according to claim 16,further comprising: decreasing an intensity of light generated by one ormore of the light emitting diodes in response to the measuredtemperature condition of the one or more light emitting diodes tocompensate for an increased temperature.
 18. The method according toclaim 16, further comprising: increasing an intensity of light generatedby one or more of the light emitting diodes in response to the measuredtemperature condition of the one or more light emitting diodes tocompensate for a decreased temperature.